Effect of Plant Growth Regulators and Packaging on Flowering, Fruit Quality and Shelf Life in Mango cv. Amrapali

Aims: To study the influence of plant growth regulators on flowering, yield, shelf life and its combined effect with packaging on quality and shelf life.

Study Design: Factorial Randomized Block Design

Place and Duration of Study: Horticulture Experimental Farm, School of Agricultural Sciences and Rural Development, Medziphema Campus, Nagaland University, Medziphema during 2006-2008.

Methodology: Pre-harvest treatments comprised of foliar spray of growth regulator naphthalene acetic acid (NAA) @ 100ppm and soil drenching Paclobutrazol (PBZ) @ 5ml/L/tree along the drip zone prior to bud differentiation in the month of September and a control (no treatment) on the mango tree. Fruits of uniform size without injury or decay were harvested from tagged trees and transported immediately to laboratory for the post-harvest experiments (polyethylene packing and control).

Results: PBZ treatment greatly influenced flowering, yield and fruit quality attributes and induced early flowering (79 days), higher flowering shoots (85.77 %), number of fruitlets per panicle (5.56), number of fruits per panicle at harvesting stage (2.23), number of fruits per tree (44.52) and fruit yield (8.62 kg per tree). TSS (11.93oBrix), TSS: Acid ratio (16.54), total sugar (8.43 %) and ascorbic acid content (47.03 mg/100g pulp) of mango fruit were also influenced by PBZ treatment. In contrast, NAA treatment showed higher fruit weight, fruit size, pulp weight and pulp: stone ratio. The post-harvest treatments consist of packing the fruits with polyethylene material of 0.3 mm thickness and 32 x 25 cm size and control. The pre- and post-harvest treatments had significant influence on the physiological loss in weight (PLW), appearance, sensory quality, firmness, total sugar, reducing sugar and non-reducing sugar of the fruit during storage. Shelf life was significantly influenced by pre- and post-harvest treatments. Shelf life was recorded more in PBZ treatment (15.33 days) closely followed by NAA treatment (15 days) where the influence reached the level of significance. Further analysis revealed that fruits from polyethylene packing showed the significantly better result with 14.89 days of shelf life as compared to control with only 13.33 days.

Conclusion: Both PBZ @ 5 ml and NAA @ 100 ppm are effective as pre-harvest treatment for enhancing the floral characters, yield and its attributes as well as physicochemical characteristics of fruits. Polyethylene packed fruits had lower PLW, better appearance and firmness, higher ascorbic acid and shelf life.